import processing.serial.*;
Serial port;    // Create an object from Serial class
String val;     // Data received from the serial port
boolean firstContact = false;

boolean button = false;

int x = 150;
int y = 150;
int w = 50;
int h = 50;

void setup() {
  port = new Serial(this, "/dev/cu.usbmodem1101", 115200);
  port.bufferUntil('\n'); 
  size(360, 360);
  background(0);
}

void draw() {
  if (button) {
    background(255);
    stroke(0);
  } else {
    background(0);
    stroke(255);
  }
  
  fill(175);
  rect(x,y,w,h);
}

void serialEvent( Serial port) {
  val = port.readStringUntil('\n');
  
  if (val != null) {
    val = trim(val);
    println(val);
    
    if (firstContact == false) {
      
      if (val.equals("A")) {
        port.clear();
        firstContact = true;
        port.write("A");
        println("contact");
      }
    }
    else {
    println(val);

    if (mousePressed == true) {                   
      port.write('1');        //send a 1
      
      if (mouseX > x && mouseX < x+w && mouseY > y && mouseY < y+h) {
      button = !button;
      }
      
      println("1");
    }

    port.write("A");
    }
  }
} //<>//